Cultivars are varieties of plants bred by plant breeders; there can be many cultivars of the same plant that are artificially selected for based on particular (desirable) phenotypic differences. A genotype refers to genetic makeup. A genotypic lineage of a group of plants are all genetically the same.
So while cultivars have the same phenotype, plants sharing similar or identical genotypes have shared DNA.
Yes, William; varieties are particular genotypes that have peculiar and definite differences (variations), such they can be called varieties... A cultivar is one that growers use for their own purpose or for commerce. Cultivars are usually developed by plant breeders. Varities are not necessarily cultivated.
@QAli,
Genotype is the genetic constitution of the species. Cultivar is something which is cultivated. A single genotype may have several cultivars.
Typically a cultivar, or variety, is clonally regenerated. The individuals then should share the same genome and are genotypes. The word "genotype" is often used in a looser sense to describe a genetic entry such a half-sib or a full-sib. That use is not technically correct.
The term "cultivar" comes from cultivated variety. It is widely used in crop sciences and is more precise than just talking of a variety that is often also confused with a botanical variety, meaning a described sub-taxon of a species.
So, in forestry it may be that "typically a cultivar is clonally regenerated" - BUT this is not necessarily the case in agriculture. Typically (sic!) a cultivar is just a cultivated variety, mainly commercially available and also registered in those countries that have variety protection legislation. A cultivar still could be a mixture of genotypes, depending whether the crop is outcrossing (for example rye) or inbreeding (for example wheat). How genotypically variable a cultivar is also depends on the breeding scheme. Therefore, cultivars from outcrossing crops may even show a certain phenotypic variability. While a cultivar of a clonally propagated crop (potato, cassava, sugarcane) will be phenotypically identical.
Consequently, there can be many genotypes contained in one cultivar, but not really several cultivars should be released from one single genotype. Even, there is a rule in the UPOV guidelines (International Union for the Protection of New Varieties of Plants - http://www.upov.int/portal/index.html.en) that - if the same genetic material already released as a cultivar in one country is released again in another country, it should not change its name.
Dear Kurt Johnsen,
Please note that genotype, half-sib and full-sib are different terms. You can go through plant breeding or genetics books for more detail. The term genotype is a classical term used to describe the genetic make up of the species. The term is absolutely correct.
I agree with Dr. Brigitte Mass, that a single cultivar/variety may have different genotypes that is why these varieties are improved by using different breeding methods from time to time. Further, all the cultivar/varieties are not cloned.
Dear M. Sidou: I am very aware that genotype has a specific definition. I was simply stating that the word is often used in a loose sense (that is, incorrectly) to refer to different types of genetic entries which I also know have differenet defininitions). I was simply trying to help the person asking the question not get mixed up from the varying use of the word.
How could we differentiate this two terms with races, lines and ecotypes.
@Dear R. Upadhaya,
To my mind, races (land race) in plants, is something produced at the level of growers through continuous cultivation and selection of seeds. Lines, the number given by the breeder while doing breeding or some other experiment. Ecotypes is related to ecology i. e., any variation in a particular species due to variation in ecological conditions.
Regards
Genotype refers to the genetic makeup of an organism (plant for instance) and its genes. Cultivar is a specific genotype of plant specially bred to have a desirable genotype that confers specific marketable traits such as disease resistance, nutritional value, yield etc.
I support Brigitte L Maass . In a big picture, cultivar has to be distinct (one's character that can be distinguished easily), uniform and stable in regard to repeated propagation.
Please, see my publication: Current definitions of useful terminology from plant taxonomy applied to Seed Science and Technology. Walter.
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